Process of preventing the formation of scaffolds in kilns.



U N ITED STATES PATENT OFFICE.

. 'ron oonsyinxe, or NEW YoRK, N. .Y., ASSIGNOR To NATIONAL iiE'rALLeReIo COMPANY, or JERSEY orrY, NEW J RsEY, A I UOHPORAIION on NEW, JERsEY.

I No. 810.059.

Specification of Letters Patent. v

FORMATION OF SCAFFOLDS IN KILNS.

Patented Jan. 16, 1906.

Application filed September 5, 1905. Serial No. 277.114.

T!) (1. whom. it may concern.-

Be it known that 1, Ton Conn KING, a citizen of the iinitedStates, residing at New York. in the county of New York and State of New York, have discovered or invented a new and useful Improvement in Methods of Preventing the Formation of Scaifolds in Kilns, of which improvement the following is a description.

.\ly invention relates to method or means for removing masses of fused material which adhere around and to the'sides of kilns or retorts used in sintering or agglomerating finely-divided metalliferous bodies. It has been found in the practical use of kilns usuall employed for this purpose'viz., long cy ind rical' retorts lined with refractory substance adapted to be rotated and in which varyin temperatures are obtained that the fuse materialhas a tendency to adhere to the sides of the retort at some point, usually near the point where the highest degree of temperature is attained, and that it is dithcnlt to remove the same when formed.

The object of the present invention is to provide a method or means for the easy and speedy removal of such formation without interferin with or stopping the operation of the kiln. accomplish this purpose by means of a suitable chemical age'ntas, for instance calcium lluorid-which is applied at the point where such formation or scaffold occurs and acting as a flux at the temperature attained in the furnace fuses the material and removes said scaffold from the sides of the kiln. In carrying out my method I preferably use a kiln or retort provided with a plurality of blowpipcs, one of which I use to bring the material to the proper fusing or partiallyfusing temperature, and the other b owpipe I use to charge calcium lluorid against the material which adheres to and around the sides of the kiln and forms scaffolds for the purpose of fusing and thus removing the same.

I have found in practice that ore low in silica forms few rings or scaffolds and that, on the contrary, ores high" in silica invariably form rings or scaffolds, and as the preponderance of all metalliferous bearing materials have more or,less silica the formationof scaffolds during the treatment of the ore in kilns of the character specified is unavoidable the removal thereof is a matter of vital importance in the operation of such'kilns. Calcium fluorid has the greatestknown affinity for silica, and consequently forms a very powerful flux and readily removes the scaifolds when charged against the same. I have found that a kiln'prod ueing from one hundred and fifty to two hundred tons of nodules from metal- .life'rous material running about five (5%) per cent. of silica will require about two hun d-rcd pounds of calcium fluorid per day, whereas material running about ten (10%) to fifteen (15%) percent. of silica requires three hundred to five hundred pounds of caland cium'fluorid per day to remove the scaffolds that form during the operation of the kiln.

I claim as my invention and desire to secure by Letters Patent i v 1. The herein-described method for removing scaffolds or rings of fused material from the sides of the kiln which consists in charging against said material, forming such rings or scaffolds, calcium fluorid.

2. The herein-described method of removin adhering masses of material from the sides of kilns or retorts which consists in charging against said material a requisite quantity of calcium fluorid to flux the same.

3. The hereindeseribed method for removing adhering masses of fused material from the sides of the kiln which consists in charging a ainst such adhering masses calcium lluorid and maintaining the material at a hi h temperature during the charging of said ca cium fluorid against the same.

' In testimony whereof I have hereunto signed my name in the presence of two subscribing witnesses.

TOM COBB KING. 

